1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method for processing a substrate using a process liquid. Examples of the substrate to be processed include a semiconductor wafer, a glass substrate for a liquid crystal display device, a glass substrate for a plasma display, a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optic disc, and a substrate for a photomask.
2. Description of Related Art
In the steps of manufacturing semiconductor devices and liquid crystal display devices, a single substrate processing apparatus for processing substrates one at a time may, in some cases, be used in order to subject a surface of a substrate such as a semiconductor wafer or a glass substrate for a liquid crystal display panel to process using a process liquid. Some of this type of substrate processing apparatus are ones so constructed as to recover the process liquid that has been used for processing the substrate and reusing the recovered process liquid for the subsequent process in order to reduce the consumption of the process liquid.
A substrate processing apparatus so configured that a process liquid is reusable comprises a spin chuck for rotating a substrate with the substrate held in a substantially horizontal posture by a plurality of chuck pins, a cup in the shape of a closed-end cylinder accommodating the spin chuck, and a splash guard provided so as to be capable of being raised and lowered to and from the cup.
A discharge groove for discharging the process liquid that has been used for processing the substrate is formed at the bottom of the cup so as to enclose the spin chuck. Further, first to third recovery grooves for recovering the process liquid that has been used for processing the substrate are formed in a triple manner, for example, at the bottom of the cup so as to enclose the discharge groove. A discharge line for introducing the process liquid to discharge process facilities (not shown) is connected to the discharge groove. Recovery lines for introducing the process liquid to recovery treatment facilities (not shown) are respectively connected to the first to third recovery grooves.
The splash guard is so configured that four umbrella-shaped members that differ in size are overlapped with one another in the vertical direction. An up-and-down driving mechanism including a ball screw mechanism or the like, for example, is coupled to the splash guard. The splash guard can be raised and lowered to and from the cup (spin chuck) by the up-and-down driving mechanism.
Each of the umbrella-shaped members has a shape that is almost rotationally symmetrical about a rotation axis of the substrate, and comprises an inclined surface inclined obliquely upward so as to come close to the rotation axis. Upper edges of the inclined surfaces of the umbrella-shaped members are positioned apart from one another in a direction along the rotation axis of the substrate on a cylindrical surface with the rotation axis of the substrate as its central axis. Consequently, an annular first recovery opening for causing the process liquid scattered from the substrate to enter a portion between an upper end of the inclined surface of the uppermost first umbrella-shaped member and an upper end of the inclined surface of the second umbrella-shaped member just below the first umbrella-shaped member is formed therebetween. Further, an annular second recovery opening for causing a process liquid scattered from the substrate to enter a portion between the upper end of the inclined surface of the second umbrella-shaped member and an upper end of the inclined surface of the third umbrella-shaped member just below the second umbrella-shaped member is formed therebetween. Further, an annular third recovery opening for causing the process liquid scattered from the substrate to enter a portion between the upper end of the inclined surface of the third umbrella-shaped member and an upper end of the inclined surface of the lowermost fourth umbrella-shaped member is formed therebetween. A discharge opening for causing a process liquid scattered from the substrate to enter a portion between the lowermost fourth umbrella-shaped member and a bottom surface of the cup is formed therebetween. The process liquids entered into the first to third recovery openings are respectively introduced into the first to third recovery grooves at the bottom of the cup. The process liquid entered into the discharge opening is introduced into the discharge groove at the bottom of the cup.
In the substrate processing apparatus having such a configuration, it is possible to successively supply a plurality of types of process liquids to the surface of the substrate to successively subject the surface of the substrate to process using the plurality of types of process liquids and to classify and recover the plurality of types of process liquids used for the process.
That is, the surface of the substrate can be subjected to the process using a first process liquid by supplying the first process liquid to the surface of the substrate while rotating the substrate by the spin chuck. The first process liquid supplied to the surface of the substrate is scattered sideward from a peripheral edge of the substrate upon receipt of a centrifugal force produced by the rotation of the substrate. If the splash guard is raised and lowered to oppose the first recovery opening to an end surface of the substrate at this time, therefore, the first process liquid scattered from the peripheral edge of the substrate can be entered into the first recovery opening and collected in the first recovery groove. The first process liquid can be recovered through a recovery line from the first recovery groove. Similarly, in a case where a second process liquid is supplied to the surface of the substrate, when the second recovery opening is opposed to the end surface of the substrate, the second process liquid scattered from the substrate can be entered. Further, in a case where a third process liquid is supplied to the surface of the substrate, when the third recovery opening is opposed to the end surface of the substrate, the third process liquid scattered from the substrate can be entered. In a case where rinsing process for washing away the surface of the substrate with deionized water by supplying the deionized water to the surface of the substrate while rotating the substrate by the spin chuck, if the discharge opening is opposed to the end surface of the substrate, the deionized water that has washed away the surface of the substrate can be collected in the discharge groove. The deionized water can be discharged through a discharge line from the discharge groove.
However, the direction of the process liquid scattered from the substrate (the scattering direction of the process liquid) differs depending on process conditions such as the rotation speed of the substrate by the spin chuck, the supply angle of the process liquid on the substrate, the supply flow rate of the process liquid to the substrate, and the type (concentration, viscosity, temperature) of the process liquid. Therefore, in such a configuration that the first to third recovery openings are arranged at predetermined positions opposed to the end surface of the substrate while the first to third process liquids are supplied to the surface of the substrate, when the process conditions are changed, the enter amount of the process liquid into the recovery opening opposed to the end surface of the substrate (the opening in which the process liquid is scheduled to be recovered) is reduced so that the recovery efficiency of the process liquid may be reduced.